1. Field of the Invention
The present invention relates to vehicular automatic transmission systems providing a plurality of gear reduction ratios, such as fully or partially automatic mechanical transmission (AMT) systems and to control systems/methods therefor. In particular, the present invention relates to control systems and methods for vehicles with throttle controlled engines and mechanical automatic transmissions wherein gear selection and shift decisions are made and executed upon measured and/or calculated parameters such as transmission output shaft or vehicle speed, transmission input shaft and engine speed, throttle position, calculated engine speed in a potentially engageable ratio, and the like. More particularly, the present invention relates to automatic transmission control systems of the type described above having a selectable mode of operation, usually referred to as a "cruise control" mode of operation, wherein a selected vehicular speed is automatically maintained and operator manipulation of the manual fuel throttle setting device is not required.
2. Description of the Prior Art
The use of automatic transmission of both the automatic mechanical type utilizing positive clutches and of the planetary gear type utilizing frictional clutches is well known in the prior art as are the control systems therefor. Electronic control systems for automatic transmissions wherein gear selection and shift decisions are made based upon certain measure and/or calculated parameters such as vehicle speed, engine speed, rate of change of vehicle speed, rate of change of engine speed, throttle position, rate of change of throttle position, full depression of the throttle (i.e. "kick-down"), actuation of the vehicle brake mechanism, currently engaged gear ratio, and the like, are well known in the prior art. Examples of such automatic transmission control systems for vehicles may be seen by reference to U.S. Pat. Nos. 3,942,393; 3,974,720; 4,028,929; 4,039,061; 4,073,203; 4,038,889; 4,226,295; 4,253,348; 4,361,060; 4,595,986; 4,551,802; 4,576,065, 4,722,248 and 4,852,006, the disclosures of all of which are hereby incorporated by reference.
Control systems/methods for automated transmission systems having a selectable mode of operation (usually referred to as a "cruise control" mode of operation) wherein a selected vehicle speed is automatically maintained without requiring the operator to manually control a fuel throttle setting device or to select or implement transmission shifts, are also well known in the prior art for both automotive and heavy duty truck vehicles.
While the prior art control systems/methods for automatic mechanical transmission systems are effective to control an automatic mechanical transmission system by selecting and implementing shifts into desirable gear ratios, such automatic control systems/methods were- not totally satisfactory when incorporated with an operator selectable cruise control mode of operation as, when operating in such mode of operation, the operator does not utilize the vehicle throttle pedal and thus the enhanced performance "kick-down" shift profiles are not available.